Defiantly the practical joker Gerhard Berger involved and a little bit of googling,
1. Jean Alesi and Gerhard Berger
2. Jean Todt
3. Lancia
4. Jean Alesi lost control of the car after Gerhard Berger unexpectedly applied the handbrake. Alesi flipped the car and ended up in hospital
5. Berger admitted to Todt who wanted to know what happened to his car that they had put "slight curb marks on the roof".